There is a great need for devices or apparatuses which make it possible to identify or detect as regards their presence at a predetermined location objects which are provided with such devices or apparatuses in contactless manner and over a certain distance. An additional need exists to be able to change the data stored in, or operating characteristics of, such devices or apparatuses (i.e. "program" the devices or apparatuses).
It is, for example, desirable to request contactless and over a certain distance identifications which are uniquely assigned to an object and which are stored in the device or apparatus so that, for example, the object may be identified. A determination may also be made as to whether or not a particular object exists within a given reading range. An example is also the case in which physical parameters such as the temperature or the pressure are to be interrogated directly at or within the object, without direct access to the object being possible. A device or apparatus of the type desired can, for example, be attached to an animal which can then always be identified at an interrogation point without direct contact. There is also a need for a device which when carried by a person permits access checking whereby only persons whose responder unit returns certain identification data to the interrogation unit are allowed access to a specific area. In this case the safeguarding of the data transfer is a very essential factor in the production of such devices. A further example of a case in which such a device is needed is the computer controlled industrial production in which, without the intervention of operating personnel, components are taken from a store, transported to a production location and there assembled to give a finished product. In this case a device is required which can be attached to the individual components so that the components can be specifically detected in the spares store and taken therefrom.
It is desirable within the context of this field to be able to update characteristics of the responder unit in a contactless manner subsequent to its manufacture. For example, it is desirable to provide means for changing the tuned frequency of a responder unit in order to optimize system performance. Perhaps it would be desirable to manufacture all responder units in a common fashion and customize the units by changing the operating frequency or another parameter. The inventive concept might be used in any of the above cases, or others, to update characteristics of the responder unit.
Another example is to implement a means to test a responder unit in a contactless fashion such that an interrogator unit might send a test command to the responder unit and receive test results back from the responder unit. Still further applications would include the sending of commands to, and receipt of parameters from, a responder unit's command decoder which may be operating a sensor or a plurality of sensors. Yet another application might be to transmit to the responder unit, again in a contactless fashion, a responder address to be stored in the responder's nonvolatile memory. In such an application, the responder might monitor incoming RF interrogation signals and only respond to further inquiries subsequent to receipt of its corresponding address signals.